1. Field of the Invention
The present invention relates to an injector.
2. Description of the Related Art
An injector which can change a fuel injecting direction, and an injector which can change a fuel spray divergent angle, are known in the prior art. Japanese Unexamined Patent Publication No. 4-5469 discloses an injector wherein a member with a nozzle hole can be moved with respect to an injection nozzle, or wherein a plurality of nozzle holes are provided and any one nozzle hole can be used, in order that the fuel injection direction can be changed.
However, in case of the injector disclosed in Japanese Unexamined Patent Publication No. 4-5469, since it is required that the member with the nozzle hole can be moved with respect to the injection nozzle, or that any one nozzle hole in the plurality of nozzle holes can be used, the structure of the nozzle hole becomes complex.
Further, Japanese Unexamined Patent Publication No. 5-44598 discloses an injector wherein an air flow is applied to an injected fuel in order to change a fuel injection direction.
However, in case of the injector disclosed in Japanese Unexamined Patent Publication No. 5-44598, since air flow applying means for apply an air flow to the injected fuel is required, the injector becomes larger.
Further, Japanese Unexamined Patent Publication No. 7-259705 discloses an injector wherein a position of the needle valve is changed with respect to an injection nozzle along a center axis of the needle valve, in order to change a fuel spray divergent angle.
However, in case of the injector disclosed in Japanese Unexamined Patent Publication No. 7-259705, since the position of the needle valve is changed with respect to the injection nozzle along the center axis of the needle valve, a fuel spray amount changes.
Further, Japanese Unexamined Utility Model Publication No. 63-140172 discloses an injector wherein a shape of a tip of a needle valve is asymmetrical with respect to a center axis of the needle valve, in order to make a difference between a fuel injecting direction and a center axis direction of an injection nozzle.
However, in case of the injector disclosed in Japanese Unexamined Utility Model Publication No. 63-140172, since the injector does not have rotating means for rotating the needle valve with respect to the injection nozzle around the center axis of the needle valve, the fuel injecting direction cannot be changed.
On the other hand, the above publications do not disclose means for controlling an angular displacement of the needle valve with respect to the injection nozzle and for changing the fuel injection direction or the fuel spray divergent angle, by preventing the needle valve with a circumferentially non-uniform tip from rotating with respect to the injection nozzle around the center axis of the needle valve, or by allowing the needle valve to rotate with respect to the injection nozzle around the center axis of the needle valve.
Also, the above publications do not disclose means for controlling an eccentricity of the center axis of the needle valve with respect to the center axis of the injection nozzle and for changing the fuel injection direction.
Further, an injector wherein a lift amount of a needle valve is changed during the valve opening period in order to change a target shape of a fuel spray is known in the prior art. The injector is, for example, disclosed in Japanese Unexamined Patent Publication No. 7-259705.
However, in case of the injector disclosed in Japanese Unexamined Patent Publication No. 7-259705, since the lift amount of the needle valve is changed during the valve opening period in order to change the target shape of the fuel spray, the target shape of the fuel spray cannot be changed while keeping a fuel injection rate constant.
Further, an injector wherein a needle valve for opening or closing a nozzle hole is provided, and the needle valve has an inner member with a tip and an outer member located outside of the inner member is known in the prior art. The injector is, for example, disclosed in Japanese Unexamined Patent Publication No. 8-177677, Japanese Unexamined Utility Model Publication No. 60-159882, and Japanese Unexamined Patent Publication No. 63-248966.
In case of the injector disclosed in FIG. 2 of the Japanese Unexamined Patent Publication No. 8-177677, Japanese Unexamined Utility Model Publication No. 60-159882, or Japanese Unexamined Patent Publication No. 63-248966, a relative position of the tip with respect to the outer member is changed. However, the relative position is not changed in accordance with a change of a target shape of a fuel spray, but is changed in accordance with a change of a fuel supply pressure with respect to the injector. That is, in case of the injector, the relative position of the tip with respect to the outer member cannot be changed in accordance with the change of the target shape of the fuel spray. Also, in case of the injector, the relative position of the tip with respect to the outer member cannot be changed while the fuel supply pressure with respect to the injector is kept constant.
Also, in case of the injector disclosed in FIG. 6 of the Japanese Unexamined Patent Publication No. 8-177677, the relative position of the tip with respect to the outer member is changed. However, the relative position is not changed in order to change the target shape of the fuel spray, but is changed in order to eject a fuel which remains in the nozzle hole during the valve closing period. That is, Japanese Unexamined Patent Publication No. 8-177677 does not disclose changing the relative position of the tip with respect to the outer member in order to change the target shape of the fuel spray.
Further, none of the above publications disclose changing the shape of the nozzle hole in accordance with the change of the lift amount of the needle valve in order to change the shape of the fuel spray.
Further, an injector which includes an injection nozzle having a nozzle hole and a valve body for opening or closing the nozzle hole, and which defines a fuel passage between an inner periphery of the injection nozzle and an outer periphery of the valve body is known in the prior art. The injector is, for example, disclosed in Japanese Unexamined Patent Publication No. 7-259705. In case of the injector disclosed in Japanese Unexamined Patent Publication No. 7-259705, a maximum lift position of the valve body is changed in order to change a shape of a fuel spray.
However, in case of the injector disclosed in Japanese Unexamined Patent Publication No. 7-259705, since the maximum lift position of the valve body is changed in order to change the shape of the fuel spray, if it is required to keep the maximum lift position of the valve body constant and, for example, if it is required to keep a fuel injection rate constant, the shape of the fuel spray cannot be changed.
On the other hand, if fuel spray shape changing means is provided outside of the injector, the shape of the fuel spray can be changed while keeping the maximum lift position of valve body constant. However, it is not preferable, since the fuel spray shape changing means is exposed to high temperature, if, for example, the injector is a direct injection type.